Patent GB-1048628-A (GB)
Abstract: 1,048,628. Programmed electric control of vibration generators. INSTITUT FRANCAIS DU PETROLE DES CARBURANTS ET LUBRIFIANTS and COMPAGNIE GENERALE DE GEOPHYSIQUE. July 15, 1963 [July 16, 1962], No. 27997/63. Heading G3N. [Also in Divisions G1, G5 and H4] In an arrangement for seismic prospecting, mechanical soil studies and road and other surveying work, a vibration generator, 7 Fig. 1 (e.g. of the hydraulic or electrodynamic type) produces a sequence of vibrations the frequency and intensity of which vary in accordance with the programme on a tape 4 carried by a rotating drum 2 and "read" by means including a light source 5 and photoelectric cell 6. Signals corresponding to the actual vibrations produced by the generator are fed via amplifier 8 to a photographic recording arrangement carried by and rotating with drum 2 and comprising mirror galvanometer 9, light source 10, mirrors 11, 12 diaphragm 13 and lens 14 to effect recording on a photographic strip 15 carried by a stationary drum 16 and signals derived from receivers 20a - 20n responsive to the vibrations reflected or refracted in the terrain being studied and fed via amplifiers 21a - 21n to similar photographic recording arrangements including photographic strips carried by stationary drums 22a - 22n. On each rotation of drum 2 which is rotatably mounted on a hollow spindle 3 and driven by motor 1 and a belt and pulley mechanism, a cam 30 carried by the drum operates a microswitch 29 to produce via means 17 a translatory motion of the drums 16, 22a - 22n, so that successive recordings are made on adjacent tracks. This arrangement is shown in Fig. 2 and comprises a pawl 27 operated against a spring 33 by electromagnet 28 on each actuation of switch 29 to produce a step-by-step movement of a rod 23 slidingly mounted in spindle 3 and connected to the drums 16, 22a etc. by means of fingers 24 which project through openings 25 in the spindle 3. The pawl 27, electromagnet 28 and spring 33 are mounted on a plate 52, which, when all the tracks have been filled, pivots about a pin 53 against a spring 32 in response to energization of an electromagnet 49 co-acting with a magnetisable element 51 carried by plate 52 and controlled by a relay 46 operated by a pulse from a track counter 45. The pivoting of plate 52 frees the ratchet member from the pawl 27 and simultaneously relay 46 starts a motor 48 which returns the rod 23 to its initial position at which operation of a switch 54 by a projection 50 interrupts the circuit. The pulse from 45 also operates via a relay 47 (Fig. 3) to start a motor which drives a photographic strip 15 through a distance equal to one recording track length to  enable a new set of sequences of vibrations to be recorded. This distance is determined by the ratio of gears 37, 38 and motor 36 is switched off via relay 47 by a pulse generated by contacts 39, 40. The strip 15 may be lubricated to reduce the effects of friction on the drum. The photoelectric system associated with the programme tape 4 (Fig. 1) may operate either by transmission or by reflection of light. Alternatively the programme tape may comprise a magnetic record scanned by a magnetic head.